The fluid dispenser command device of the invention can be usefully employed for distributing fuels, lubricating oils and other workshop fluids, especially for automobiles. A typical application example is indeed in a car repair and maintenance workshop, where lubricating oil and other fluids are stored in quite large centralized tank units rather than in cans or other relatively small containers.
The centralized units in the prior art are generally one or more storage tanks, equipped with one or more electric pumps which supply the pressurized fluids to one or more hand-held guns through one or more feed pipes. The feed pipes comprise tubes which are normally maintained under pressure by a feed pump, which latter disconnects automatically when a predetermined pressure value (Pmax) is reached. Each gun is equipped with a trigger for manual activation by an operator, who thus controls exit of the pressurized fluid and, in consequence a drop in pressure inside the pipe. When the pressure reaches a minimum threshold level (Pmin) the pump automatically starts up to ensure fluid supply to the gun, and continues in operation until the operator releases the trigger.
The prior art teaches dispenser guns including a trigger lock to hold the trigger open during operation and free the operator's finger. Prior-art guns also include a command device which automatically stops fluid distribution when the fluid volume already dispensed reaches a pre-set quantity. In this case the fluid delivery quantity is set before the gun is operated, and the trigger is locked in the open position, so that it can be safely left to do its work and will stop automatically once the pre-set quantity has been dispensed.
A gun of this type, however, has a serious drawback. If by mistake the trigger should be locked open and left to work without having first preset a desired quantity of fluid to be dispensed, there is the great possibility of considerable spillage. In short, then, the presence of an operator is still required with prior-art dispenser guns.